The present invention relates to a screw compressor.
More specifically the present invention relates to a screw compressor that at least comprises a compression chamber that is formed by a compression housing, in which a pair of meshed helical compressor rotors are rotatably mounted, which have rotor shafts that extend along a first and second axial direction that are parallel to one another, whereby the screw compressor also contains a least a drive motor, and which is provided with a motor chamber formed by a motor housing in which a motor shaft is rotatably mounted, and this motor shaft extends along a third axial direction and which drives at least one of the aforementioned two helical compressor rotors.
Such screw compressors are already known, which however present a number of disadvantages or which are open to improvement.
In order to be able to drive the compressor rotors, in the known screw compressors generally the motor shaft of the drive motor is directly or indirectly, for example via a drive belt or a gearwheel transmission, coupled to the rotor shaft of one of the compressor rotors.
Hereby the rotor shaft of the compressor concerned must be adequately sealed, which is far from easy.
Indeed, a certain pressure supplied by the screw compressor prevails in the compression housing, which has to be screened off from the compressor sections that are not under this pressure or from the ambient pressure.
For such applications, a “contact seal” is often used.
The rotor shaft of the compressor rotor concerned however turns at very high speeds, such that such a type of seal brings about enormous power losses during the operation of the screw compressor, resulting in a reduced efficiency of the screw compressor.
Moreover, such a “contact seal” is subject to wear, and if it is not carefully installed such a “contact seal” is very sensitive to the occurrence of leaks.
Another aspect of the known screw compressors of the type described above that is open to improvement, is that both the drive motor and the screw compressor have to be provided with lubrication and cooling, that generally consist of separate systems and thus are not attuned to one another, require a number of different types of lubricants and/or coolants, and are thereby complicated or expensive.
In addition, in such known screw compressors with separate cooling systems for the drive motor and compressor rotors, the possibilities for recovering the lost heat stored in the coolants in an optimum way are not fully utilised.